The invention concerns the controlling of termites in building construction. Termites, insects of the order isoptera, have about 2,000 species, about 200 of which are known to be pests and cause damage to crops, buildings and furniture. Termite distribution is primarily tropical. They are also prevalent in the subtropics and temperate zones. In North American they reach as far north as Maine and Vancouver.
The present invention is directed to subterranean dwelling species, which are dependent on moisture in the soil and which reach and destroy buildings and furnishings through foundations, either by wood in contact with the soil, or by cracks in slabs and foundations. Termite nymphs divide into worker, soldier and alates or reproductors. New colonies are established by winged adults who are weak flyers, often blown in the wind for a few yards or hundreds of feet. They alight, shed their wings, pair and nest in soft wood or soil. The nests are sealed to preserve moisture. A first batch of eggs is laid, and in two to five years a colony matures. The queen may become as large as four inches long, laying more than 30,000 eggs a day during a lifetime, which may stretch over 20 or more years. The tendency of colonies to establish close to each other and the rapid development of established colonies cause the species to become extremely destructive. The termites are equipped with mouth parts for chewing wood, and their guts contain protozoans for dissolving wood. Once colonies are well established, it is difficult to destroy them.
Many systems have been devised for destroying wood dwelling termites. The most satisfactory may be expensive and difficult fumigations. Subterreanean termites are mostly attacked by poisoning the ground before construction and by filling a trench around a construction with chemicals, usually chlorinated hydrocarbons. Some below-the-ground pipe systems have been proposed, which install rigid pipes beneath the surface of the ground, especially beneath vertical walls. Insecticides are periodically released from the pipes.
Many problems remain with termite control. Foremost of the problems is the need to control termites with a minimal level of chemicals so that the chemicals do not migrate to ground water and cause long-term pollution. Another problem that exists is the distribution of termite control chemicals in a suitable manner to ensure destruction of all the termites without overloading a ground system with the chemicals. Problems exist in ensuring against penetrations of slabs and foundations by unobserved cracks.